A form of pump and motor utilized in hydraulic power transmission comprises a rotor having a plurality of spaced radial vanes rotatable therewith and slidable relative thereto in slots provided in the rotor. The rotor and vanes cooperate with the internal contour of a cam to define one or more pumping chambers between the outer periphery of the rotor and the cam contour through which the vanes pass carrying fluid from an inlet port to an outlet port. Cheek plates are associated with each side of the cam and rotor through which the fluid flows to and from the rotor.
It has heretofore been recognized that it is essential for efficient operation of the pump to apply pressure to a chamber at the underside or base of the vanes in order to maintain them in contact with the cam. In the past pressure has been applied continuously or intermittently to the undersides of the vanes. In the continuous pressure arrangement, pressure is applied even when the vanes are in low pressure zones and has resulted in excessive cam and vane tip wear. In the intermittent pressure arrangement, pressure is applied to the vanes only when the vanes are in high pressure zones and only centrifugal force is utilized to urge the vanes toward the cam when the vanes are in low pressure zones. As a result the contact of the vanes with the cam is not positive during some portions of the travel so that efficiency is adversely affected.
It has heretofore been suggested and commercial devices have been made wherein additional pressure chambers are associated with each vane. The chamber at the base of each vane is commonly known as the under vane chamber and is subjected to cyclically changing pressure. The additional chambers are commonly known as the intra-vane chambers and are subjected to continuous high pressure. Typical devices are shown in U.S. Pat. Nos. 2,919,651 and 2,967,488. In such an arrangement, the contact of the vanes with the cam is controlled at all times by fluid pressure to the intra-vane and under vane chambers.
In order to feed high pressure fluid to the intra-vane or high pressure chamber, it has been necessary to utilize passages in the cheek plates in the zones of low pressures and axial grooves in the rotor intersecting the vane slots. Since the fluid in these passages and grooves is at a high pressure, the fluid tends to leak through the interface between the cheek plates and rotor to the low pressure zones. In addition, leakage from the intra-vane chamber to the under vane chamber may occur between the vanes and slots due to tilting of the vane in the slot by the forces acting on the vane in a tangential direction.
In order to feed fluid to the under vane chamber from the pumping chambers the rotor is formed with a radial hole extending and intersecting the under vane chamber from the periphery of the rotor between the vane slots. However, with devices of this general type the radial holes in the rotor tend to weaken the rotor at the intersection of the radial hole and the under vane chamber. As a result it has been necessary to limit the maximum pump pressure to avoid rotor failure.
It has heretofore been suggested that the intra-vane chambers be fed with fluid through an internal passage formed entirely within the rotor and that a check valve be associated with each vane to control the flow of fluid to the chambers. A typical arrangement of this type is shown in U.S. Pat. No. 3,223,044.
The present invention is directed to a fluid pressure energy translating device which has increased efficiency and is easier and less costly to manufacture.
In the copending U.S. patent application Ser. No. 275,948 of Harry T. Johnson, filed June 22, 1981, having a common assignee with the present application, a generally annular internal feed passage is formed entirely within the rotor and communicates with the intra-vane pressure chambers. A radial passage along each side of each vane extends from the outer end or tip of each vane to the inner end or base of each vane thereof to supply cyclically changing fluid pressure to the under vane chambers. An arcuate valving groove is formed in each cheek plate alongside the rotor in the high pressure zones and communicates with the radial passages as the rotor rotates. Axial openings in the side of the rotor extend to and intersect the annular passage. The axial openings are adapted to register with the arcuate groove as the rotor rotates relative to the cheek plates to supply fluid under pressure from the radial passages in the vanes through the arcuate grooves and axial openings to the annular passage and, in turn, to the intra-vane chambers.
As shown in U.S. Pat. No. 3,223,044, the rotor is made in two halves, each of which has an annular groove in a radial face so that when the faces of the two halves are brought into contact and joined together, the two grooves face one another to form the annular passage. When a rotor is made in this manner, it is costly, it is difficult to control the joining of the two halves to insure against fluid leakage and the resultant rotor is weak because axial fluid pressure forces acting on the two halves tend to force the halves away from one another.
The present invention is directed to the manufacture of a rotor of a fluid pressure energy translating device which is easier and less costly to manufacture and which results in a rotor that has higher strength.
In accordance with the invention, the method comprises forming an annular groove in the periphery of a solid body, closing the open side of the groove to provide the annular passage, thereafter forming radial vane slots in the body intersecting the annular passage and forming axial openings in the body intersecting the annular passage.